feat(tasks): aggregated task progress FAB + bottom sheet

- Add TaskAggregator (server/stores) to unify TaskCreate/TaskUpdate/TodoWrite
- Broadcast task-state snapshots via new WS event on tool events + reconnect
- TaskFab: SVG progress ring with fade-out on completion, reappears on new tasks
- TaskBottomSheet: full task list with dependencies, activeForm, expandable description
- Remove inline TodoWrite rendering (TaskProgress), filter task tools from chat flow
- Rebuild task state from JSONL history on server restart/reconnect

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

server/ws-types.ts

@@ -37,6 +37,8 @@ export const WS = {
   // Cross-AI Review
   REVIEW_STARTED: 'review-started',
   REVIEW_ENDED: 'review-ended',
+  // Task Progress
+  TASK_STATE: 'task-state',
 } as const;
 
 export type WsType = typeof WS[keyof typeof WS];